Merge array and hash in ruby if key appears in array

Question

I have two arrays one = [1,2,3,4,5,6,7] and two = [{1=>'10'},{3=>'22'},{7=>'40'}]

Two will have one.length hashes or less. I want a new array of values from two if it's key appears in one, if not then use 0. The new array would be [10,0,22,0,0,0,40] What is the best way to do this?

Your two is invalid.

sawa
– sawa

2014-03-12 13:37:01 +00:00
Commented Mar 12, 2014 at 13:37 — sawa
– sawa, Commented Mar 12, 2014 at 13:37
That is also invalid.

sawa
– sawa

2014-03-12 13:44:06 +00:00
Commented Mar 12, 2014 at 13:44 — sawa
– sawa, Commented Mar 12, 2014 at 13:44

toro2k · Accepted Answer · 2014-04-10 14:23:01Z

9

I'd do it using Enumerable#reduce and Hash#values_at:

two.reduce({}, :merge).values_at(*one).map(&:to_i)
# => [10, 0, 22, 0, 0, 0, 40]

edited Apr 10, 2014 at 14:23

answered Mar 12, 2014 at 13:47

toro2k

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sawa · Accepted Answer · 2014-03-12 14:57:03Z

4

h = [{1 => '10'}, {3 => '22'}, {7 => '40'}].inject(:merge).to_h
one.map{|e| h[e].to_i}
# => [10, 0, 22, 0, 0, 0, 40]

edited Mar 12, 2014 at 14:57

answered Mar 12, 2014 at 13:38

sawa

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3 Comments

toro2k Over a year ago

You should pass an empty hash as the first argument to inject, otherwise [].inject(:merge) # => nil and h[e] would raise a NoMethodError.

sawa Over a year ago

@toro2k Your point is correct, but I would rather do to_h. That looks prettier to me.

Alok Anand Over a year ago

@sawa we can combine 2 answers two.inject(:merge).values_at(*one).map(&:to_i)

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